The invention relates to a yarn winding apparatus for continuously winding an advancing yarn onto bobbin tubes serially delivered to a winding position. An apparatus of this type is disclosed in European Patent Application 5664 and U.S. Pat. No. 4,210,293.
In copending and commonly owned U.S. application Ser. No. 07/454,723, filed Dec. 21, 1989, a winding apparatus is disclosed wherein the yarn transferring mechanism includes a plate, which is guided between the full and the empty winding spindle and which displaces the yarn in such a manner that the yarn loops a substantial distance about the empty bobbin tube on the winding spindle to facilitate the catching of the yarn by the catching slot on the bobbin tube. Also, this winding apparatus serves to wind a continuously advancing yarn without waste.
According to the German Patent 32 11 603, and U.S. Pat. No. 4,431,138, the problem of transferring a yarn loss free from a full package to an empty tube and of causing it to be caught by the latter is solved in that the yarn is removed from a yarn traversing mechanism and guided into a normal plane in which a yarn catching slot of the bobbin tube is located, which is placed on the empty spindle. Simultaneously, the full package is axially displaced in such a manner that the yarn advancing in the catching plane continues to wind on the full package. The empty spindle is also moved into the yarn path between the yarn traversing mechanism and the operating spindle in such a manner that the yarn and the bobbin tube on the empty spindle having the same direction of movement contact each other in the normal plane of the yarn catching slot (i.e. common rotation catching). As a result, it is accomplished that on the one hand the yarn continues to be wound as a bead on the full package, while on the other hand the yarn can be placed into the catching slot provided in the empty tube. However, the displacement of the winding spindle with full packages becomes a problem of mechanical engineering when packages of a very considerable thickness are wound and/or several, for example, four packages are each formed by one yarn on a winding spindle, which is normally supported in a cantilever fashion.
U.S. Pat. No. 3,913,852 describes the so-called counter-rotation yarn catching, which is in contrast to the above-described common rotation yarn catching. In the counter-rotation yarn catching, the yarn advancing to the full package is likewise lifted out of the yarn traversing mechanism and pulled out as a loop by a transferring device. In so doing, the strand of yarn advancing to the transferring device is guided in the plane of a catching slot provided in the empty tube and has there a direction of movement, which upon its contact is opposite to the direction of movement of the empty tube, while the strand of yarn moving away from the transferring means is guided onto the full package and wound to form a bead. Due to the very large deflection of the yarn in the transferring device, the tension in the strand of yarn advancing to the transferring device and the empty tube drops very significantly. This drop of tension is further enhanced in that the empty tube moves against the running direction of the yarn in the zone of the common contact. Although this procedure ensures a reliable catching of the yarn, there also exists the risk that the yarn slackens at the moment it is caught so considerably that the yarn path is disturbed. In particular, laps may form on the feed roll system preceding the takeup machine, thereby causing the winding process to break down.
European Application 88104937.4 and U.S. Pat. No. 4,867,385 disclose a procedure for the reliable catching of the yarn by the common rotation method, wherein the yarn which is pulled off behind the empty spindle is braked in such a manner that it forms a lap on the winding tube of the empty spindle.
It is accordingly an object of the present invention to provide a yarn winding apparatus of the described type which achieves a highly reliable common rotation catching of the yarn, without the displacement of a winding spindle. In so doing, and for the purpose of avoiding changes in the yarn tension, special importance is attached to the fact that the yarn transfer procedure, such as the transfer of the yarn from the full package to the empty tube by catching the yarn on the empty tube, and the tearing or cutting of same from the full package, occurs in such a short time that also the formation of a bead on the full package is kept within narrow limits.